CVE-2026-91990

Description

Tornado before 6.5.8 contains a memory amplification vulnerability in parse_multipart_form_data that splits multipart data before validating the max_parts limit. Attackers can send crafted multipart requests with many parts to create large transient lists, exhausting server memory and causing denial of service.

CVSS Vector

References

• https://github.com/tornadoweb/tornado/security/advisories/GHSA-8423-8fgw-73vq
• https://www.vulncheck.com/advisories/tornado-before-6.5.8-memory-amplification-dos-via-multipart
• https://github.com/tornadoweb/tornado/security/advisories/GHSA-8423-8fgw-73vq